Abstract: Techniques for spatial spectral holography include a doped crystal comprising Thulium doped into a host crystal of Yttrium Lutetium Aluminum Garnet wherein a concentration of Thulium atoms is less than 3 atomic percent. Techniques further include an apparatus with a source for optical electromagnetic radiation and a cryocooler configured to maintain an operating temperature in a range from about 3 Kelvin to about 6 Kelvin. The cryocooler includes a first optical window. The apparatus also includes a doped crystal comprising Thulium doped into a host crystal of Yttrium Lutetium Aluminum Garnet disposed inside the cryocooler in a position to be illuminated by incident optical electromagnetic radiation derived from the source. The apparatus also includes a detector configured to detect optical electromagnetic radiation emitted from the doped crystal. Techniques include a method for using at least one of the above doped crystals.

Abstract: Techniques for producing an arbitrary broadband waveform include storing a first waveform in a circulating coherent storage device. A next waveform is generated. A shifted replica is generated by shifting, by a frequency shift one of the next waveform or the waveform in the storage device. A combined waveform is stored by coherently combining the shifted replica and one of the next waveform or the waveform in the storage device which waveform is not frequency shifted. An apparatus includes a source of a carrier frequency waveform, and a modulator configured to impose the next waveform on the carrier frequency waveform. The apparatus also includes a circulating coherent storage device configured to store a coherent interaction between multiple waveforms. The apparatus also includes a frequency shifter configured to generate a shifted replica by shifting, by a frequency shift, one of the next waveform or a waveform in the storage device.

Abstract: A method and apparatus for producing an arbitrary broadband waveform includes generating a first narrowband waveform and generating a frequency-shifted replica by frequency shifting the first narrowband waveform by a frequency shift. A second narrowband waveform is also generated. A broadband waveform is generated by combining the frequency-shifted replica and the second narrowband waveform.

Abstract: An apparatus includes a single or dual output port, dual-drive Mach-Zehnder Interferometer configured to generate a first optical signal in one path, and to generate a second optical signal in a different path. The apparatus also includes an optical spectrum analyzer configured to receive output from at least one port of the dual-drive Mach-Zehnder Interferometer. A method includes causing radio frequency signals from two different antennae to modulate an optical carrier at a corresponding drive of a dual-drive Mach-Zehnder Interferometer, and causing output from at least one port of the Mach-Zehnder Interferometer to be directed to an optical spectrum analyzer. The method further comprises determining arrival angle at each of a plurality of frequencies in the radio frequency signals based on output from the optical spectrum analyzer.